It is known that the quality of the finished paper product in paper manufacturing process depends to a large extent upon the press felt. Therefore it is very important for paper manufacturer to get knowledge about the press felt prevailing condition and properties, such as thickness, tension profile, permeability, etc. There is a need to provide reliable measuring devices and methods, which are capable of mapping those properties over the entire surface of the fabric. The width of the fabric, up to 10 meters and sometimes greater, makes it difficult to carry out these measurements.
Typically the thickness of the fabric is measured by a dial indicator; which allows measuring only a few points across the fabric. There are two main disadvantages of this method. Firstly, it is impossible to get an entire thickness profile of the fabric. And secondly, since the measurement is manual, it is difficult to obtain an exact coordinate across the width of the fabric for the point being measured. Due to these uncertainties, it is difficult to compare thickness results measurements performed at different time.
Current devices for thickness measurement to do not allow changing measurement trajectory, repeating measurements in some critical areas of an object, moving backwards, and in general choose a two-dimensional trajectory being optimal for a particular object under study. There is a need for a measurement device being able to move in any direction within the plane of the object.
The problems described above in conjunction with the measurement of the thickness profile also apply to the measurement of the tension profile, permeability and other parameters of the sheet-like objects. There is a need to repeatedly carry out measurements of these parameters over the entire surface of the fabric in a simple and reliable way.